1. 1 Linda McCaig and David Woodwell 2006 Data Users Conference July 11, 2006 Analyzing Data from the NAMCS and NHAMCS

2. 2 Overview Background Data uses Survey methodology Current and proposed survey items User considerations Methodological studies Data dissemination NCHS Research Data Center

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4. 4 National probability sample surveys National Ambulatory Medical Care Survey (NAMCS) –Patient visits to non-federal office- based physicians National Hospital Ambulatory Medical Care Survey (NHAMCS) –Patient visits to EDs and OPDs of non- federal short-stay hospitals

5. 5 Original NAMCS survey goals National statistics Professional education Health policy formulation Quality assurance

6. 6 NAMCS history Survey began in 1973 Annual data collection through 1981 (NORC) Conducted in 1985 (NORC) Annual began again in 1989 (Census)

7. 7 NHAMCS history Survey began in 1992 Annual data collection (Census)

8. 8 How are NAMCS and NHAMCS data used?

9. 9 Data uses Understand health care practices Track certain conditions and prescribing patterns Find health disparities Examine the quality of care Measure Healthy People 2010 objectives Serve as benchmark for states

10. 10 Data users Over 100 journal publications in last 2 years Medical associations Government agencies Institute of Medicine Health services researchers University and medical schools Broadcast and print media

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12. 12 1/ Significant increase since 1997 (p<.01) 18.6 38 18.7 47.4 0 10 20 30 40 50 60 Minutes.0 1994 2004 1997 2004 Office visit duration Waiting time in emergency departments 1/ Average length of time for duration of office visits and emergency departments waiting times

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14. 14 Source: National Hospital Ambulatory Medical Care Survey, 1992-2001 Citation: Edlow JA, Kim S, Pelletier AJ, Camargo CA Jr. National study on emergency department visits for Transient Ischemic Attack, 1992-2001. Acad Emer Med 2006;April 11 Percent of ED visits for transient ischemic attack in which a CT or MRI was ordered or performed

15. 15 Percent of pediatric ED visits with analgesic prescription by pain score Drendel AL et al. Arch Intern Med 2006;117(5):1511-16.

16. 16 Percent of ED visits for attempted suicide according to arrival time Overall Attempted suicide Doshi A et al. Ann Emerg Med 2006;46(4):369-75. a.m.p.m.

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18. 18 Trends in office-based visit rates by children and adolescents that included antipsychotic treatment Olfson M et al. Arch Gen Psyc 2006;63:679-685

19. 19 Percent of prescriptions for UTI by drug class in physician offices, OPDs, and EDs Kallen AJ et al. Arch Intern Med 2006;116(6):635-639.

20. 20 NAMCS and NHAMCS Methodology

21. 21 NAMCS Scope Includes non-federal, office-based physicians Excludes physicians whose main activity is teaching, research, administration, hospital-based care, or who are unclassified as to activity and those in certain specialties

22. 22 In-Scope NAMCS locations Freestanding clinic/urgicenter Federally qualified health center Neighborhood and mental health centers Non-federal government clinic Family planning clinic HMO Faculty practice plan Private solo or group practice

23. 23 Out-of-Scope NAMCS locations Hospital EDs and OPDs Ambulatory surgicenter Institutional setting (schools, prisons) Industrial outpatient facility Federal Government operated clinic Laser vision surgery

24. 24 NAMCS Sample design 112 geographic PSUs ~ 3,000 physicians ~ 25,000 visits –1 week reporting period

25. 25 NHAMCS Scope OPD was intended to be parallel to the NAMCS in the hospital setting General medicine, surgery, pediatrics, ob/gyn, substance abuse, and “other” clinics are in-scope Ancillary services are out of scope

26. 26 NHAMCS Sample design 112 geographic PSUs ~ 500 hospitals ~ 400 EDs and ~ 250 OPDs ~ 37,000 ED and ~ 35,000 OPD visits –4-week reporting period

27. 27 Gaining cooperation Advance letters Endorsement letters Public relations materials Conversion of refusal

28. 28 Data collection procedures Induction visit by Census field representative (FR) FR training of office/hospital staff Take every number Prospective or retrospective method

29. 29 Items collected on Patient Record form (PRF) Patient characteristics – age, race, sex Visit characteristics – reason for visit, diagnosis, medication Provider characteristics – physician specialty, hospital ownership

30. 30 Repeating fields Reason for visit (3) Cause of injury (3) Diagnosis (3) Ambulatory surgical procedures (2) Medications (8)

31. 31 Data processing Data are coded and keyed by Constella Group Inc. Quality control procedures Edit checks by NCHS

32. 32 Coding systems used A Reason for Visit Classification (NCHS) ICD-9-CM – diagnoses – external causes of injury – procedures Drug coding system (NCHS) National Drug Code Directory

33. 33 Therapeutic classification system through 2004 Since 1985, FDA’s NDC therapeutic classification has been used Limitations – Discontinued by FDA – Only one level of sub-classification

34. 34 Therapeutic classification system - Multum Lexicon Starting in 2005 Advantages – Two levels of sub-classification – Regular updates

35. 35 Example: Classification of paroxetine NDC – 0600 central nervous system 0630 antidepressants Multum Lexicon – 242 psychotherapeutic agents 249 antidepressants – 208 SSRI antidepressants

36. 36 2004 NAMCS PRF

37. 37 Patient Record form - common items Patient’s zip code Date of visit Date of birth Sex Ethnicity

38. 38 Patient Record form - common items Race Source of payment Temperature and blood pressure Reason for visit Diagnosis

39. 39 Patient Record form – common items Diagnostic/screening services Medications and injections Providers seen Visit disposition

40. 40 Injury/poisoning/ adverse effect items External cause – narrative text since 1997 ED – Intentionality – Work-related

41. 41 NAMCS and OPD PRF - unique items Does patient use tobacco Counseling/education/therapy Surgical procedures Time spent with physician (NAMCS only)

42. 42 NAMCS and OPD PRF continuity of care items Patient’s primary care physician/provider Was patient referred for visit Patient seen before Seen how many times in past 12 months Major reason for visit Episode of care Other physicians share care

43. 43 ED Patient Record form - unique items Arrival time Time seen by physician Discharge time Mode of arrival Immediacy Pulse and orientation

44. 44 ED Patient Record form - unique items Presenting level of pain Alcohol related visit Work related visit Procedure checklist

45. 45 ED Patient Record form - continuity of care items Seen ED within last 72 hours Episode of care – Initial or followup visit

46. 46 Modifications to 2005-06 ED PRF On – Patient residence – Discharged from any hospital within last 7 days – Drug given in ED or prescribed at discharge – Reason patient was transferred Off – Alcohol related visit – Episode of care

47. 47 Modifications to 2005-06 ED PRF Information on patients admitted to from the ED – Type of unit – Admission time – Hospital discharge date – Principal hospital discharge diagnosis – Discharged dead or alive

48. 48 Modifications to 2005-06 NAMCS/OPD PRFs On – Pregnant (LMP) or gestation week – Chronic disease checklist – Disease management program – Height and weight – Medications – new or continued – Non-medication treatment Off – Episode of care – Do physicians share care – Cause of injury

49. 49 ED PRF - new items for 2007-08 Respiratory rate How many times seen in this ED in last 12 months? Type of MRI and CT scan – Head or other Procedure checkboxes – more specific

50. 50 NHAMCS induction form - new items for 2005-06 Electronic medical records Mass casualty preparedness – Drills, exercises ED staffing, capacity, and ambulance diversion – Percent of ED board certified physicians – Number of hours ED was on ambulance diversion – Plans to expand ED physical space

51. 51 NHAMCS induction form - new items for 2007-08 Critical Access Hospital (CAH) Transplant services Outsourcing of radiographs ED observation unit

52. 52 Examples of facility-level data

53. 53 Emergency Pediatric Services and Equipment Supplement (EPSES) Funded by the Health Resources and Services Administration Added as a supplement to the 2002-03 and 2006 NHAMCS – Services related to treating children – Availability of pediatric supplies

54. 54 Cross-classification of EDs by ED pediatric visit volume and inpatient pediatric structure ED pediatric visit volume Percent of EDs Middleton KR, Burt CW. ADR #367.

55. 55 Cross-classification of pediatric ED visits by ED pediatric visit volume and inpatient pediatric structure Percent of pediatric ED visits ED pediatric visit volume Middleton KR, Burt CW. ADR #367.

56. 56 Bioterrorism and mass casualty preparedness Funded by the DHHS ASPE 2003-05 NAMCS Induction Interview – Diagnosis of terror-related conditions – Assistance in making a diagnosis – Reporting a suspect case 2003-04 NHAMCS supplement – Hospital response plan, training, and resources

57. 57 Percentage of hospitals that trained their staff in emergency response by subject area Niska RW, Burt CW. ADR #364.

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59. 59 2003-04 NHAMCS Supplements Hospital inpatient occupancy rate ED capacity and staffing – Number of treatment spaces – Percent of vacant nursing positions – Physicians employed by hospital or contractor Ambulance diversion

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61. 61 Percent distribution of EDs by time on ambulance diversion and metropolitan statistical area status Time on diversion Percent of EDs Burt CW, McCaig LF, Valverde RH. Ann Emerg Med. 2006;47:317-326

62. 62 Percent of office-based physicians and hospital OPDs and EDs using electronic medical records, 2001-2003 Burt CW, Hing E. ADR #353.

63. 63 Overview Updates to NAMCS and new items on the Physician Induction Interview (PII) User considerations Methodological studies HIPAA Data dissemination NCHS Research Data Center

64. 64 Improvements to NAMCS in 2006 New stratum of 104 Community Health Centers (FQHC & Urban Indian Health Centers) – 3 @ each for a total of 312 providers – MDs, DOs, mid-level providers New stratum of oncologists (n=200) Increased sample to primary care physicians (n=50 each GFP, IM, OB/GYN)

65. 65 NAMCS induction form - new item for 2005 Electronic medical records – If yes, does it include… Patient demographics Computerized orders for prescriptions…

66. 66 NAMCS induction form - new items for 2006 On-site tests or procedures Electronic medical records – If yes, does it include… Patient demographics Computerized orders for prescriptions – If yes, Are there warning for drug interactions… Pay for performance (P4P)

67. 67 NAMCS induction form - new items for 2007-08 Length of time for appointment Telemedicine

68. 68 Encounter vs. person data NAMCS and NHAMCS are record- based surveys Estimates are in terms of visits and not persons Not population-based surveys (NHIS) Cannot calculate incidence or prevalence rates from our estimates

69. 69 Sample weight Sample data MUST be weighted to produce national estimates Estimation process – Adjusts for survey and item nonresponse – Makes several ratio adjustments within and across physician specialties and hospitals

70. 70 Sampling error NAMCS and NHAMCS are not simple random samples Clustering effects: – Providers within PSUs – Visits within physician practice or hospital Must use generalized variance curve or special software (e.g., SUDAAN) to calculate SEs for all estimates, percents, and rates

71. 71 Reliability criteria Estimate based on at least 30 raw cases are reliable Estimate has a relative standard error (RSE) less than 30 percent are reliable Both conditions must be met

72. 72 Ways to improve reliability of estimates Combine NAMCS, ED and OPD data to produce ambulatory care visit estimates Combine multiple years of data

73. 73 Nonsampling error Frame coverage Reporting and processing errors Biases due to survey and item nonresponse Incomplete responses

74. 74 Minimizing nonsampling error Improve sample frame for better coverage Encourage uniform reporting and eliminate ambiguities Pretest survey items and procedures Perform quality control procedures – consistency and edit checks Train Census field representatives

75. 75 NAMCS Response rate

76. 76 NHAMCS Response rates ED OPD

77. 77 Attempts to improve response rate Publicity Eliminating questions that have a high item non-response Methodological studies

78. 78 Methodological studies Complement study (1997-1999) – Missing 11% of visits to physicians classified as not office-based Nonresponse follow-up survey (1998) – Another in 2006

79. 79 Methodological studies NAMCS Motivational insert (2000) NAMCS and OPD PRF length (2001) Incentives test (2002)

80. 80 HIPAA No directly identifiable information collected PHS Act 308(d) / Title 15 Data Use Agreement w/ Limited Dataset IRB approval w/ waiver of patient authorization Accounting Document

81. 81 HIPAA 1-800 telephone number Respondent website Training Written instructions CD-ROM Self-study Follow-up

82. 82 Impact of HIPAA on NAMCS and NHAMCS Induction process in hospitals is longer due to additional levels of approval process Less likely to allow FR abstraction Response rate not directly affected Easy reason to refuse

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85. 85 Future releases 2005 NAMCS & NHAMCS in Spring 2007 2003-04 medications report ADR combining all 3 setting together

86. 86 Outside research Journal articles – List on Ambulatory Care web site Text books Department level publications – Health US

87. 87 Microdata files Downloadable files NAMCS, 1973-2004 NHAMCS, 1992-2004 CD-ROMs NAMCS, 1990-2003 NHAMCS, 1992-2003 Tapes/cartridges (NTIS) NAMCS, 1973-1997 NHAMCS, 1992-1997

88. 88 Enhanced public-use files New survey items and facility level data SAS input statements, variable labels, value labels, and format assignments for 1993- 2004 SPSS syntax files, Stata.do and.dct files for 2002-2004

89. 89 Enhanced public-use files Sample design variables – Masked variables for multi-stage sampling are available: 1993-2004 NAMCS and NHAMCS – Starting in 2002, NAMCS & NHAMCS masked variables have been available for use in software using 1-stage sampling. Prior years with formula – Stating in 2003, we only released masked variables for use in software using 1-stage

90. 90 2001* 3- & 4-Stage design variables 2003 2002 1-Stage design variables only 1-Stage design variables 3- & 4-Stage design variables Design Variables—Survey Years *Plan to re-release years with 1-stage design variables.

91. 91 Ratio of masked to unmasked SUDAAN standard errors using four-stage WOR Source: Inquiry 40: 401-415 (Winter 2003/2004)

92. 92 Average comparison ratios by alternative standard error method and type of setting Type of settingMasked 4- stage WOR SUDAAN Masked 1- stage WR SUDAAN Masked SURVEY- MEANS GVC All settings1.03 1.020.84 Physician’s offices 1.02 1.010.93 Hospital OPD0.991.031.020.94 Hospital ED1.031.06 0.91 Source: Inquiry 40: 401-415 (Winter 2003/2004)

93. 93 Scatter plot of masked and unmasked 4-stage WOR SUDAAN SE for all settings

94. 94 Where to get more information Ambulatory Care information booth Call Ambulatory Care Statistics Branch at (301) 458-4600 Public Use Documentation or…

95. 95 http://www.cdc.gov/nchs/about/major/ahcd/ahcd1.htm

96. 96 NCHS Research Data Center

97. 97 Why the Research Data Center? Have access to information not available on public use files –Patient: zip code linked income, education, or urbanicity status –Provider: physician gender and age, board certification, teaching hospital, medical school affiliation, ED size, provider weight –Geographic: state and county FIPS codes

98. 98 Data Center - cont. Can merge with contextual variables (e.g., ARF, NHIS, Census, NHDS) –Health status level –HMO penetration –Physician and specialist supply –Medicaid reimbursement –Air quality –Percent in poverty

99. 99 Data Center rules Submit a proposal Cannot use data to identify patients or providers or geographic location of providers Cannot remove data files Fee – onsite / remote / file construction

100. 100 I need more information ! Visit the Research Data Center booth E-mail: rdca@cdc.gov Website: www.cdc.gov/nchs/r&d/rdc.htm Call (301) 458-4277

101. 101 Thank You Linda McCaig – NHAMCS data lmccaig@cdc.gov David Woodwell – NAMCS data dwoodwell@cdc.gov